Nikon D2H manual 109, AF-Assist for Multi-Area AF, TTL Flash Control, Flash control

AF-Assist for Multi-Area AF

The SB-800 features AF-assist illumination linked to the D2H focus areas, allowing autofocus to be used even at night, regardless of the subject’s posi- tion in the frame. AF-assist illumination can be used in all AF-area modes, including single-area AF, dynamic-area AF, group dynamic-AF, and dynamic- area AF with closest-subject priority. If the subject is poorly lit, the AF-assist illuminator will light automatically when single-servo AF is used in combina- tion with an AF-Nikkor lens (if a lens with an angle greater than 35 mm is used, the illuminator may not light if the focus area at the left or right edge of the frame are selected).

i-TTL Flash Control

When used with the D2H and set to TTL, the SB-800 automatically uses one of the following types of i-TTL flash control:

Flash control Description

Taking Photographs—Flash Photography

i-TTL Balanced

Fill-Flash for

Digital SLR

Standard

i-TTL Flash for

Digital SLR

Speedlight emits series of nearly invisible preflashes (monitor pre- flashes) immediately before main flash. Preflashes reflected from objects in all areas of frame are picked up by five-segment TTL flash control sensor or 1,005-pixel RGB sensor and are analyzed in com- bination with information from matrix metering system to adjust flash output for natural balance between main subject and ambi- ent background lighting. When type G or D lens is used, distance information is included when calculating flash output. Precision of calculation can be increased for non-CPU lenses by providing lens data (focal length and maximum aperture; 124–127). Not avail- able when spot metering is used.

Flash output adjusted to ensure main subject is correctly exposed; brightness of background is not taken into account. Recommended for shots in which main subject is emphasized at expense of back- ground details, or when exposure compensation is used. Standard i-TTL flash for digital SLR is activated automatically when spot meter- ing is selected.

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